[Python-ideas] π = math.pi

[Pavol Lisy]

Sorry for probably stupid question! Is something like ->

    class A:
        def __oper__(self, '⊞', other):
            return something(self.value, other)

    a = A()
    a ⊞ 3

thinkable?

On 6/3/17, Guido van Rossum <guido at python.org> wrote:
> OK, I think this discussion is pretty much dead then. We definitely
> shouldn't allow math operators in identifiers, otherwise in Python 4 or 5
> we couldn't introduce them as operators.
>
> On Fri, Jun 2, 2017 at 5:10 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>
>> On Fri, Jun 02, 2017 at 04:29:16PM -0700, Guido van Rossum wrote:
>>
>> > Are those characters not considered Unicode letters? Maybe we could add
>> > their category to the allowed set?
>>
>> They're not letters:
>>
>> py> {unicodedata.category(c) for c in '∑√∫∞'}
>> {'Sm'}
>>
>>
>> That's Symbol, Math.
>>
>> One problem is that the 'Sm' category includes a whole lot of
>> mathematical symbols that we probably don't want in identifiers:
>>
>> ∴ ∣ ≈ ≒ ≝ ≫ ≮ ⊞  (plus MANY more variations on = < and > operators)
>>
>> including some "Confusables":
>>
>> ∁ ∊ ∨ ∗ ∑ etc
>>
>> C ε v * Σ
>>
>> http://www.unicode.org/reports/tr39/
>>
>> Of course a language can define identifiers however it likes, but I
>> think it is relevant that the Unicode Consortium's default algorithm for
>> determining an identifier excludes Sm.
>>
>> http://www.unicode.org/reports/tr31/
>>
>> I also disagree with Ivan that these symbols would be particularly
>> useful in general, even for maths-heavy code, although I wouldn't say no
>> to special casing ∞ (infinity) and maybe √ as a unary square root
>> operator.
>>
>>
>>
>> --
>> Steve
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>
>
>
> --
> --Guido van Rossum (python.org/~guido)
>